The present invention relates to a solar cell material. More specifically, the present invention relates to a porphyrin-based photosensitizer dye for dye-sensitized solar cells.
Various research studies have been carried out in an attempt to develop alternative energy sources that can replace conventional fossil fuels and solve an approaching energy crisis. Virtually inexhaustible solar energy has attracted a great deal of notice among the alternative energy sources such as wind power, atomic power, and solar power. Solar cells, or photovoltaic cells (PV cells), are considered as a major candidate for obtaining energy from the sun, since they can convert sunlight directly to electricity, provide long term power at a low operation cost, and be free of pollution associated with energy generation.
Recently, Grätzel and O'Regan have proposed a new type of solar cells known as dye-sensitized solar cells (DSSC), which have drawn much attention because they present a highly promising alternative to conventional silicon based solar cells. In nanocrystalline TiO2 solar cells sensitized with a dye, poly-pyridyl ruthenium (Ru) complexes are used as photosensitizer dyes. The advantages of using such Ru complexes are that they have broad absorption in the near UV/visible regions, and appropriate excited-state oxidation potential for electron injection into the conduction band of TiO2. However, on one hand, in the visible region, the absorption coefficient of poly-pyridyl Ru complexes is not large enough; on the other hand, the cost, rarity, and environmental issues of Ru complexes also limit their wide application.
It is known that in the photosynthetic cores of bacteria and plants, solar energy is collected by porphyrin-based chromophores and the captured radiant energy is efficiently converted to chemical energy. In view of such inspiration, porphyrin and phthalocyanine derivatives have been synthesized and used for photovoltaic solar cells. Thus, various porphyrin derivatives can be used to develop cheaper and safer photosensitizer dyes with a high absorption coefficient in the visible region.